The present disclosure relates to printer devices and more particularly to a gear clutch assembly and method for operating different rollers in the printer device using a single motor.
In many printer devices, an intermediate transfer surface, such as a transfer drum, is used to deliver printer ink from a print head to a print or receiving medium such as paper. More specifically, ink is ejected from jets in the print head onto the transfer drum creating a liquid layer of ink. The receiving medium is then brought into contact with the transfer drum and the ink image is transferred and fused or fixed to the receiving medium.
To assist in the transfer and fixing of the ink image, a transfix roller is often utilized to apply a pressure to the receiving medium thereby pressing the receiving medium against the transfer drum. When or around the time the receiving medium engages the transfer drum for transfixing of the image on the receiving medium, the transfix roller is moved from an unloaded or disengaged position toward a loaded or engaged position. In the loaded position, the receiving medium is sandwiched between the transfer roller and the transfer drum. After the ink image is transfixed on the receiving medium and the receiving medium is ready or about ready to disengage from the transfer drum, the transfix roller is moved from the loaded position toward an unloaded position to permit the receiving medium to exit from the transfix roller and transfer drum. The transfix roller remains in the unloaded position until the next transfix operation occurs.
After the ink is transfixed to the receiving medium from the transfer drum, the transfer drum requires conditioning for a subsequent ink jetting from the print head. Typically, a drum maintenance system is used to condition the transfer drum for receipt of the next ink image. The drum maintenance system, when activated, moves from staged or disengaged position to an operating or engaged position. In the engaged position, a roller included in the drum maintenance system applies oil or other similar functioning substance to the transfer drum. The oil reduces the probability that ink sprayed onto the transfer drum will stick to the transfer drum during the transfix operation. The drum maintenance system also includes an elastomeric or rubber blade that approaches or engages the transfer drum when the drum maintenance system is in the engaged position. The blade meters the oil being applied to the transfer drum. While the drum maintenance system is in the engaged position, the transfix roller remains in its idle unloaded position. Upon completion of the drum maintenance operation, the drum maintenance system is moved to its staged position.
Typically, the transfix roller and the drum maintenance system are cam driven. For instance, each of the transfix roller and the drum maintenance system may be driven by independent cam mechanisms, namely a transfix cam mechanism and a drum maintenance cam mechanism. In one prior art system, two separate motors were used to drive the individual cam mechanisms. The first motor drives the transfix cam mechanism and the second motor drives the drum maintenance cam mechanism, with appropriate switching to activate each motor when needed. A disadvantage of the two motor system is the cost for including two such motors in a print device and the spatial and volumetric constraints within print devices.
In a second prior art system, a single motor is used to drive both the transfix cam mechanism and the drum maintenance cam mechanism. Independent control of the cam mechanisms is achieved through the use of electromagnetic clutches or electromagnetic solenoids. There are several disadvantages in the single motor/electromagnetic clutch or solenoid system. First, electromagnetic clutches and solenoids are unreliable as they tend to fail and render their print devices inoperable. Second, although not always as costly as the two motor system, electromagnetic clutches and solenoids are still costly to include in competitive print devices.
Third, single motor/electromagnetic clutch or solenoid systems do not permit operation of the cam mechanisms simultaneously. Simultaneous or concurrent operation allows the drum maintenance system to be moved toward the engaged position at the same time that the transfix roller is moved from the loaded position to the unloaded position. Such simultaneous operation increases the speed and efficiency of the print device.
One solution to these problems of the prior single motor systems is shown in FIGS. 1-3. FIG. 1 shows a print device 10 having a transfer drum 12 rotatably mounted therein. The print device 10 further includes a print head (not shown) for spraying ink onto the transfer drum 12, a preheater (not shown) for heating a print or receiving medium, such as a sheet of paper, prior to said receiving medium engaging the transfer drum 12, a transfix roller (not shown) for applying pressure to the receiving medium against the transfer drum 12 as the receiving medium passes the transfer drum 12, and a drum maintenance system 16 (FIG. 2). The drum maintenance system 16 includes a roller for applying an oil or like substance to the transfer drum 12 to prevent ink from sticking thereto and a rubber blade for metering the oil applied to the transfer drum 12. A motor driven gear clutch assembly 20 operates or controls the engagement and disengagement of the transfix roller as well as the engagement and disengagement of the drum maintenance system 16.
With reference to FIG. 3, the gear clutch assembly 20 is shown with a first housing piece 22 (FIG. 1) removed to reveal the details of the gear clutch assembly 20. Gears of the gear clutch assembly 20 are in meshing relation with a transfix driving gear 26 and a drum maintenance driving gear 28. The transfix driving gear 26 is a component of a transfix cam shaft assembly 30 which includes a transfix cam shaft 32 and first and second cams 34, 36. Rotation of the transfix driving gear 26 will rotate the cam shaft 32 and the cams 34, 36 mounted thereto. The drum maintenance driving gear 28 is a component of a drum maintenance cam shaft assembly 40 which includes a drum maintenance cam shaft 42 and first and second cams 44, 46 mounted to the cam shaft 42. Rotation of the drum maintenance driving gear 28 will rotate the cam shaft 42 and the cams 44, 46. A motor 48 is separately connected to the gear clutch assembly 20 to drive the gears of the gear clutch assembly 20.
The gear clutch assembly includes a swing arm 50 that selectively engages one or both of the output gear trains 52, 54 to drive the corresponding transfix and drum maintenance driving gears 26, 28. As described in more detail in U.S. Pat. No. 6,585,368, the disclosure of which is incorporated herein by reference, controlled pivoting of the swing arm selectively engages the output gear trains 52, 54 to the drive motor 48. Certain movements of the swing arm 50 allow both forward and reverse rotation of each output gear. Rotation of the swing arm is produced by rotation of a driven gear of the swing arm and controlled by various pins and stops. Independent output gear engagement by the swing arm movement depends in part upon missing teeth in the two output gears.
There remains a need for a gearbox capable of switching between multiple output gears, especially in drive systems for devices like printing devices. The need is particularly acute for providing a low cost, quiet gearbox capable of high torque transmission.